1. Field of the Invention
The present invention relates to a fuel cell stack including a stack body formed by stacking a plurality of power generation cells in a stacking direction, and terminal plates, insulating members, and end plates provided at both ends of the stack body in the stacking direction. Each of the power generation cells has an electrolyte electrode assembly and a separator. The electrolyte electrode assembly includes a pair of electrodes, and an electrolyte interposed between the electrodes.
2. Description of the Related Art
For example, a solid polymer electrolyte fuel cell employs a polymer ion exchange membrane as a solid polymer electrolyte membrane. In this fuel cell, the solid polymer electrolyte membrane is interposed between an anode and a cathode to form a membrane electrode assembly (MEA). Each of the anode and the cathode includes electrolyte catalyst (electrode catalyst layer) and porous carbon (gas diffusion layer). The membrane electrode assembly is sandwiched between separators (bipolar plates) to form a power generation cell.
Normally, a predetermined number of the power generation cells are stacked together to form a stack body. At both ends of the stack body in the stacking direction, terminal plates, insulating plates, and end plates are provided to form a fuel cell stack. In use, for example, the fuel cell stack is mounted in a fuel cell electric vehicle as an in-vehicle fuel cell stack.
In some of power generation cells of the fuel cell stack, in comparison with the other power generation cells, the temperature is decreased easily due to heat radiation to the outside. For example, in the power generation cells provided at ends of the fuel cell stack in the stacking direction (hereinafter also referred to as the “end power generation cells”), since a large amount of heat is radiated to the outside, e.g., from the terminal plates and the end plates adjacent to these end power generation cells, the decrease in the temperature is significant.
In this regard, for example, a fuel cell stack disclosed in Japanese Laid-Open Patent Publication No. 2001-068141 is known. As shown in FIG. 11, the fuel cell includes a stack body 2 formed by stacking a plurality of cell units 1. At both end of the stack body 2 in the stacking direction, a pair of current collection plates 3a, 3b are provided. Further, a pair of insulating plates 4a, 4b are provided outside the current collection plates 3a, 3b for electric insulation.
Manifold plates 5a, 5b are provided outside the insulating plates 4a, 4b to apply a force for tightening components of the entire fuel cell by the manifold plates 5a, 5b. 
In each of the cell units 1, a coolant water channel 6 is formed along an electrode surface. An inlet and an outlet of the coolant water channel 6 are connected to a coolant water supply manifold 7a and a water guidance manifold 7b. 
A coolant water inlet 8a and a coolant water outlet 8b are formed in the manifold plate 5a. The coolant water inlet 8a is connected to the coolant water supply manifold 7a extending in the stacking direction, and the coolant water outlet 8b is connected to the water guidance manifold 7b through a coolant water channel 9. The coolant water channel 9 is formed on the manifold plate 5b, and the coolant water channel 9 has a turn for allowing the coolant to flow upward, and then, downward.